Nonfelting wool and antifelt finishing process

ABSTRACT

The present invention relates to a specific process in which wool is initially subjected to a plasma treatment and then to a wet chemical treatment with a finishing agent, which provides nonfelting wool in a technically simple and easily handleable manner.

BACKGROUND OF THE INVENTION

The invention relates to nonfelting wool and a process for antifeltfinishing by treating the wool with a plasma and also to anaftertreatment with a specific finishing agent.

The textile processing industry has a particular interest in reducingthe felting tendency of wool, especially of raw wool or unprocessedwool. The felting of wool is customarily reduced by finishing withspecific auxiliaries.

Isocyanates, especially self-dispersing isocyanates, have long been usedas auxiliaries for the antifelt finishing of textiles. However,self-dispersing isocyanates, the use of which has become preferred, donot always provide a completely satisfactory antifelt finish on thetreated textiles when used alone.

DE-A 198 587 34 and DE-A 198 587 36 disclose the antifelt finishing ofwool by combination of a plasma treatment with an after-treatment usingsuch self-dispersing isocyanates. To apply these self-dispersingisocyanates to the wool, it is first necessary to prepare aqueousdispersions. Since such dispersions have only a very limited shelf life,due to the ensuing crosslinking reaction of the isocyanate end groups inwater, they have to be prepared relatively shortly before use for wooltreatment.

DE-A 2 035 172 describes a process for the antifelt finishing of wool inwhich the wool is treated with a polyurethane latex liquor and thefabric is dried and subsequently cured. To be able to prepare laticessuitable for finishing, organic solvents and external emulsifiers haveto be used at the prepolymerization stage. The prepolymers initiallyobtained are subsequently fully polymerized by addition of a chainextender.

DE-A 26 57 513 discloses a process for the antifelt finishing of woolusing reaction products of polyisocyanates with hydroxyl-functionalcompounds.

DD 5381 describes a process for preparing hydrophilic basicpolyurethanes from diisocyanates, diprimary aliphatic glycols containingone or more basic tertiary nitrogen atoms in open chain, and diprimaryglycols without basic nitrogen. Possible applications mentioned for suchproducts are very generally films, fibers, sizing and hand modifyingagents, animalizing agents, and sizing agents for paper.

DD 5379 describes a process for preparing hydrophilic basicpolyurethanes from diisocyanates and nitrogenous glycols containing, inthe chain between the hydroxyl groups, one or more tertiary nitrogenatoms in which third valencies are saturated by monovalent alkyl groupsthat do not have more carbon atoms than the shortest carbon chainbetween a hydroxyl group and tertiary nitrogen. Possible applicationsmentioned for such products are very generally films, fibers, sizing andhand modifying agents, animalizing agents, and sizing agents for paper.

DD 5367 describes very specific polyurethanes prepared fromdiisocyanates and N,N′-di[oxyalkyl]piperazines.

It is an object of the present invention to provide an improved processfor the antifelt finishing of wool.

SUMMARY OF THE INVENTION

The present invention accordingly provides a process for antifeltfinishing of wool comprising

(a) exposing wool to a plasma in a pretreatment, and

(b) treating the plasma-treated wool with an aqueous dispersion ofcationic polyurethanes.

DETAILED DESCRIPTION OF THE INVENTION

The plasma treatment of the wool in step (a) of the process of theinvention is effected either as a low temperature plasma treatment atreduced pressure or as a corona treatment at normal pressure.

The low temperature plasma treatment is extensively described in DE 19616 776 C1 (counterpart of U.S. Pat. No. 6,103,068, hereby expresslyincorporated by reference). The wool is exposed to a radiofrequencydischarge of a frequency of 1 kHz to 3 GHz and a power density of 0.003to 3 W/cm³ at a pressure of 10⁻² to 10 mbar for a period of 1 to 600 secin the presence or absence of non-polymerizing gases. The process ispreferably carried out under a pressure of 0.1 to 1 mbar and for aperiod of 2 to 5 minutes.

The actual low temperature plasma is generated by feeding inelectromagnetic radiation in the frequency range of 1 kHz to 3 GHz. In apreferred variant, the low temperature plasma is generated via amicrowave discharge of 1 to 3 GHz (the power density at the outcouplingis especially 0.1 to 15 W/cm²). The electromagnetic radiation can besupplied continuously or pulsed. A pulsed high frequency dischargehaving a pulsing frequency of up to 10 kHz is especially advantageous.

When non-polymerizing gases are additionally used as plasma processgases, they are introduced into the plasma treatment space at a flowrate of up to 200 l/h. Useful non-polymerizing gases are in particularoxygen, nitrogen, noble gases, especially argon, air, or mixturesthereof.

The design and construction of a low temperature plasma reactor areknown. Preference is given to using an electrodeless reactor having anoutcoupling for microwaves. The wool to be treated is preferably placedunderneath the outcoupling unit. The distance of the wool from theoutcoupling unit is preferably 1 to 30 cm, especially 2 to 10 cm. Afterthe wool to be treated has been introduced into the reactor, the reactoris suitably evacuated with vacuum pumps in such a way that the pressureduring the plasma treatment is in the range of 10⁻² to 10 mbar,preferably 0.1 to 1 mbar. A continuous flow-through operation ispreferably carried out by applying specific vacuum locks that make itpossible for the material to enter and exit without leakage.

Alternatively to this embodiment of the low temperature plasma treatmentunder low pressure, the wool can also be subjected to a corona treatmentat a pressure in the range of 100 mbar to 1.5 bar, preferably atatmospheric pressure. The corona treatment is described in detail inDE-A 198 587 36 (counterpart of U.S. Pat. No. 6,242,059, herebyincorporated by reference).

The corona treatment subjects the wool to a high frequency dischargehaving a power density of customarily 0.01 to 5 Ws/cm² for a period of 1to 60 seconds (preferably 2 to 40 seconds, particularly 3 to 30 seconds)in the presence or absence of non-polymerizing gases. Suitablenon-polymerizing gases are air, oxygen, nitrogen, noble gases, ormixtures thereof.

The actual plasma is generated by applying an alternating voltage of 1to 20 kV in the frequency range between 1 kHz to 1 GHz (preferably 1 to100 kHz) to electrodes, one or both poles being provided with aninsulator material. The alternating voltage can be supplied eithercontinuously or with individual pulses or with pulse trains and pausesin between.

The design and apparatus configurations of a corona reactor are knownand described, for example, in DE-A 197 31 562. The corona treatment ispreferably carried out via electric discharges in the atmosphericpressure region, for which the wool to be treated is initiallyintroduced into a sealed, tight treatment housing, charged there withthe working gas, i.e., the above-mentioned non-polymerizing gas, andsubsequently exposed to an electric barrier discharge in a gap betweenthe two treatment electrodes. The distance of the wool material from thetreatment electrodes is 0 to 15 mm, preferably 0.1 to 5 mm, particularly0.3 to 2 mm. The treatment electrodes are preferably constructed asrotatable rolls either or both of which are coated with electricallyrefractory dielectric material.

Performing the corona treatment at a pressure in the range from 100 mbarto 1.5 bar, preferably at atmospheric pressure, has the advantage overthe low pressure plasma treatment at 10⁻² to 10 mbar that the equipmentneeded is very much less complicated than in the case of the lowpressure treatment. Vacuum pumps are not required, nor is it necessaryto fit special vacuum locks.

The special effect of the plasma treatment in step (a) of the process ofthe invention might be explained as follows. The liquid present in thefiber desorbs from the fiber surface as water vapor/gas during theprocess. High energy electrons, ions, and also highly excited neutralmolecules or radicals are formed and act on the surface of the fiber,the water vapor desorbed from the fiber ensuring that particularlyreactive particles are formed in the immediate vicinity of therespective fiber surface and these particularly reactive particles acton the surface.

Following the plasma treatment in step (a) of the process according tothe invention, the wool is treated in step (b) with an aqueous solutionof cationic polyurethanes.

These cationic polyurethanes have a weight average molecular weight ofat least 14,000, preferably at least 16,000, particularly preferably atleast 18,000, especially at least 20,000. The upper limit of themolecular weight is customarily 200,000, preferably 180,000,particularly preferably 150,000.

The cationic polyurethanes are obtainable by reaction of

(i) organic polyisocyanates of the general formula (I)

Q[NCO]_(p),  (I)

 where

p is from 1.5 to 5, and

Q is an organic radical, and

(ii) one or more bis- and/or polyhydroxy compounds containing at leastone tertiary nitrogen atom and at least two hydroxyl groups,

wherein the cationic character of the polyurethane is generated bysubsequent protonation or alkylation of the tertiary nitrogen atoms.

Optionally, the cationic polyurethanes used according to the inventionare prepared by additionally using

(iii) one or more bis- and/or polyhydroxy compounds that contain nonitrogen atoms and have molecular weights of 62 to 5,000. Useful organicpolyisocyanates (i) of the general formula (I)

Q[NCO]_(p),  (I)

where Q and p are each as defined above and include, for example, thefollowing three types:

(1) aliphatic, cycloaliphatic, araliphatic, and aromaticpolyisocyanates,

(2) aliphatic, cycloaliphatic, araliphatic, and aromatic polyisocyanatesthat contain isocyanurate and/or uretidione and/or allophanate and/orbiuret and/or oxadiazine structures, and

(3) isocyanate prepolymers that are obtainable by reaction of aliphatic,cycloaliphatic, araliphatic, and aromatic diisocyanates and polyestersand/or polyethers.

The aliphatic, cycloaliphatic, araliphatic, and aromatic polyisocyanates(2) with isocyanurate and/or uretidione and/or allophanate and/or biuretand/or oxadiazine structures are preparable according to conventionalprior art processes from corresponding aliphatic, cycloaliphatic,araliphatic, and aromatic diisocyanates.

The isocyanate prepolymers (3) are reaction products of aliphatic,cycloaliphatic, araliphatic, and aromatic diisocyanates and polyestersand/or polyethers, which optionally may contain unconverted, freepolyisocyanates.

Illustrative examples of aliphatic, cycloaliphatic, araliphatic, andaromatic diisocyanates useful as type (1) or for preparing types (2) and(3) are 1,4-diisocyanatobutane, 1,6-diisocyanatohexane,1,5-diisocyanato-2,2-dimethylpentane,2,2,4-trimethyl-1,6-diisocyanatohexane, 1,3- and1,4-diisocyanatocyclohexane,1-isocyanato-1-methyl-4-isocyanatomethylcyclohexane,4,4′-diisocyanatocyclohexylmethane, 2,4- and2,6-diisocyanato-1-methylbenzene, 4,4′-diisocyanatodiphenylmethane, orany mixtures of these diisocyanates.

Preferred examples of modified diisocyanates (2) are trimerizationproducts of hexamethylene diisocyanate and of its biuret-basedderivatives, mixtures of the uretidione and the trimerization productsof hexamethylene diisocyanate, and the uretidione of toluenediisocyanate.

Preferred examples of the isocyanate prepolymers (3) are reactionproducts of toluene diisocyanate or of hexamethylene diisocyanate withpolyhydric alcohols, for example, of toluene diisocyanate withtrimethylol-propane.

Preference is given to organic polyisocyanates of the general formula(I)

Q[NCO]_(p),  (I)

where

p is from 1.5 to 5 (especially 2), and

Q is an aliphatic hydrocarbon radical having 2 to 18 (especially 6 to10) carbon atoms, a cycloaliphatic hydrocarbon radical having 4 to 15(especially 5 to 10) carbon atoms, an aromatic hydrocarbon radicalhaving 6 to 15 (preferably 6 to 13) carbon atoms, or an araliphatichydrocarbon radical having 8 to 15 (preferably 8 to 13) carbon atoms.

Preferred bis- and/or polyhydroxy compounds (ii) are those of thegeneral formula (II)

HO—(CHR¹)_(m)—NR²—(CH₂R¹)_(n)—OH  (II),

where

n and m are independently from 1 to 6,

R¹ is in each case independently hydrogen or a straight-chain orbranched C₁-C₄-alkyl radical wherein, along the (CHR¹)_(n) and(CHR¹)_(m) alkylene chains, R¹ can alternately from carbon atom tocarbon atom be not only hydrogen but also a straight-chain or branchedC₁-C₄-alkyl radical, and

R² is straight-chain or branched C₁-C₁₀-alkyl (especially C₁-C₆-alkyl),C₁-C₁₀-cycloalkyl (especially C₅-C₆-cycloalkyl), C₆-C₁₂-aryl (especiallyphenyl), or a —CH₂)_(r)—OH radical in which r is from 1 to 6.

Illustrative examples of bis- and/or polyhydroxy compounds (ii) of thegeneral formula (II) are N-methyldiethanolamine, N-ethyldiethanolamine,N-butyldiethanolamine, N-methyldipentanolamine-1,5,N-ethyldipentanolamine-1,5, triethanolamine, reaction products of fattyamines with two moles of ethylene oxide or propylene oxide oralkoxylation products of the aforementioned compounds, preferably oftris[2-(2-hydroxyethoxy)ethyl]amine.

Illustrative examples of bis- and/or polyhydroxy compounds (iii) thatcontain no nitrogen atoms and have molecular weights of 62 to 5,000 areethylene glycol, propanediol-1,2, propanediol-1,3, butanediol-1,4,butanediol-1,3, butanediol-2,3, butanediol-1,2, butenediol-1,4,butynediol-1,4, pentanediol-1,5, neopentyl glycol, hexanediol-2,5,hexanediol-1,6,3-methylpentanediol-1,5,2,5-dimethylhexane-2,5-diol,octadecanediol-1,12, diethylene glycol, dipropylene glycol, triethyleneglycol, tripropylene glycol, tetraethylene glycol, tetrapropyleneglycol, and also further higher polyethylene and polypropylene glycols,glycerol, trimethylolpropane, 2-hydroxymethyl-2-methyl-1,3-propanediol,1,2,6-hexanetriol, or pentaerythritol.

It is further possible to use polyethers and polyesters having a weightaverage molecular weight of up to 5,000 (preferably up to 3,000,particularly preferably up to 2,000) as component (iii). Polyethers areobtainable from the above-mentioned bis- and/or polyhydroxy compounds asstarter molecules by reaction with ethylene oxide, propylene oxide,and/or butylene oxide according to known processes of the prior art.Polyesters are likewise obtainable from the above-mentioned bis- and/orpolyhydroxy compounds, namely by esterification with industriallyavailable di- or tricarboxylic acids according to known processes of theprior art.

Particularly useful cationic polyurethanes are obtained by reaction of

(i) organic polyisocyanates of the general formula (I)

Q[NCO]_(p),  (I)

 where

p is from 1.5 to 5 (especially 2), and

Q is an aliphatic hydrocarbon radical having 2 to 18 (especially 6 to10) carbon atoms, a cycloaliphatic hydrocarbon radical having 4 to 15(especially 5 to 10) carbon atoms, an aromatic hydrocarbon radicalhaving 6 to 15 (preferably 6 to 13) carbon atoms, or an araliphatichydrocarbon radical having 8 to 15 (preferably 8 to 13) carbon atoms,and

(ii) bis- and/or polyhydroxy compounds (ii) of the general formula (II)

HO—(CHR¹)_(m)—NR²—(CH₂R¹)_(n)—OH  (II),

 where

n and m are independently from 1 to 6 and are especially identical andfrom 1 to 3,

R¹ is in each case independently hydrogen or a straight-chain orbranched C₁-C₄-alkyl radical wherein, along the (CHR¹)_(n) and(CHR¹)_(m) alkylene chains, R¹ can alternately from carbon atom tocarbon atom be not only hydrogen but also a straight-chain or branchedC₁-C₄-alkyl radical, and

R² is straight-chain or branched C₁-C₁₀-alkyl (especially C₁-C₆-alkyl),C₁-C₁₀-cycloalkyl (especially C₅-C₆-cycloalkyl), C₆-C₁₂-aryl (especiallyphenyl), or a —(CH₂)_(r)—OH radical in which r is from 1 to 6,especially from 1 to 3,

and the cationic character of the polyurethanes is generated bysubsequent protonation or alkylation of the tertiary nitrogen atoms.

Very particular preference is given to using in step (b) of the processaccording to the invention cationic polyurethanes obtained by reactionof

(i) 2,4-toluene diisocyanate or 2,6-toluene diisocyanate or mixtures ofthese isomers with

(ii) N-methyl- or N-butyldiethanolamine,

wherein the cationic character is generated by treating the reactionproducts with one of the acids hydrochloric acid, sulfuric acid, formicacid, acetic acid, or propionic acid.

To prepare the cationic polyurethanes to be used in step (b) of theprocess according to the invention, the bis- and/or polyhydroxycompounds (ii) and optionally (iii) are customarily initially charged inan aprotic auxiliary solvent.

It is advantageous to choose the amount of polyhydroxy compounds (ii)and optionally (iii) in such a way as to still obtain a readilyprocessible cationic polymer.

Illustrative examples of aprotic solvents for the reaction are alkylether acetates, glycol diesters, toluene, carboxylic esters, acetone,methyl ethyl ketone, tetrahydrofuran, dimethylformamide, andN-methylpyrrolidone.

This initially charged solution then has added to it the organicpolyisocyanate (i) with stirring. Excesses of organic polyisocyanatemust be avoided in the process, since this leads to undesirablesecondary reactions due to the presence of a multiplicity of tertiaryamine structures from the components (ii) and optionally (iii).

Conventional catalysts such as dibutyltin dilaurate, tin(II) octoate, or1,4-diazabicyclo[2.2.2]octane and/or further compounds containingtertiary nitrogen or tin and also optionally bismuth compounds or othercustomary polyurethane chemistry catalysts in amounts of 10 to 1,000ppm, based on the reaction components, can be used to speed up thereaction. The reaction is carried out in the temperature range up to130° C., preferably in the range from 20 to 80° C. The upper limit ofthe reaction temperature is set by the boiling point of the solvent; itcan be advantageous to conduct the reaction under evaporative cooling.The reaction is monitored by determining the NCO content by titration orby measurement of the IR spectra and evaluation of the NCO band at 2260to 2275 cm⁻¹ toward the end of the reaction and is complete when theisocyanate content is not more than 0.1% by weight above the value thatis obtained at complete conversion under the given stoichiometry or whenthe NCO band has disappeared.

It is advantageous for the molar ratio of component (i) to component(ii) plus optional component (iii) to be set in such a way as to have anapproximately stoichiometric ratio of the NCO and OH end groups present.

The polyurethanes are customarily rendered cationic in one of thefollowing two ways:

First, it is possible to dilute the solution of the polyurethane asprepared with an aqueous acid after the reaction. Useful acids include,for example, hydrochloric acid, sulfuric acid, formic acid, acetic acid,or propionic acid. Formic acid and acetic acid are preferred. Thisaddition of an acid protonates the tertiary nitrogen atoms fromcomponent (ii) and, if used, component (iii). It is customary to use astoichiometric amount of acid, based on the nitrogen atoms, so thatideally complete protonation is obtained. The solvent is then distilledoff until the theoretical solids content is obtained.

On the other hand, it is also possible for the polyurethane prepared asdescribed above to be converted into a polyurethane having permanentcationic charges by partial or complete alkylation. This can beaccomplished according to conventional processes directly followingpreparation, either in organic solution or else in the aqueous state.The alkylating agents used are preferably methyl chloride, methyliodide, dimethyl sulfate, or methyl p-toluenesulfonate.

In step (b) of the process according to the invention the aqueousdispersion of the cationic polyurethane is applied to the wool at a pHof 2 to 7, preferably 3 to 6; particularly preferably 4 to 6 andespecially 4.5 to 5.5. The application temperature is customarily in therange from 20 to 80° C., preferably from 30 to 70° C., particularlypreferably from 30 to 60° C.

The concentration of the aqueous dispersion of the cationicpolyurethane, based on the solids content of polyurethane, in thefinishing liquor is 0.5 to 75 g/l, preferably 1 to 50 g/l.

The treatment with the aqueous solution of cationic polyurethanes of thewool in step (a) is effected according to customary processes of theprior art. Suitable is, for example, a batchwise method by the exhaustprocess or a continuous method by dipping, roll application, padding,application of a mist or spray, or backwasher application optionallyusing dyeing machines, stirrers, and the like to agitate the treatmentliquor. The liquor ratio can be chosen within wide limits and can bewithin the range of (20 to 5):1, preferably (10 to 5):1.

Unexpectedly, the cationic polyurethanes are very quick to exhaust ontothe wool in step (b) of the process according to the invention. This isall the more surprising as, at the slightly acidic pH customarily usedfor the aqueous liquor, the wool itself has a cationically chargedsurface, whereby the cationic polyurethanes should actually be repelled,which would result in worse exhaustion characteristics for thepolyurethanes.

The treatment in step (b) is optionally followed by a furtherafter-treatment step (c) in which the wool is treated with furtherauxiliaries and additives. Useful such auxiliaries and additivesinclude, for example, flow control agents, levelling agents,surfactants, deaerators, wetting agents, distancing agents, exhaustionauxiliaries, and fixatives.

The cationic polyurethanes used in the process of the invention haveincomparably better stability in aqueous dispersion than theself-dispersing isocyanates known from DE-A 198 587 34 and DE-A 198 58736. The corresponding dispersions therefore have far longer use livesand can be prepared and utilized with long lead times.

The present invention further provides the nonfelting wool,characterized in that the wool

(a) is exposed to a plasma in a pretreatment, and

(b) treated with an aqueous dispersion of cationic polyurethanes.

The two steps (a) and (b) are subject to the above remarks for theprocess.

The wool used in the process of the invention may be selected from avery wide range of wool materials, for example, raw wool after the rawwool wash, dyed or undyed wool stubbing, dyed or undyed wool yarn,roving, drawn-loop knits, formed-loop knits, wovens, or cloths. Thewater content of the wool is customarily 4 to 40% by weight, preferably5 to 30% by weight, particularly preferably 6 to 25% by weight,especially 8 to 15% by weight.

The wool of the present invention, finished with cationicpoly-urethanes, differs substantially from wool finished withself-dispersing isocyanates. The self-dispersing isocyanates known fromDE-A 198 587 34 and DE-A 198 587 36 are compounds that are located inthe low molecular weight range and are prepared, for example, byreaction of organic diisocyanates such as diisocyanatobutane withmonofunctional polyalkylene oxide alcohols, amines, or thiols. Theseself-dispersing isocyanates crosslink on the surface of the wool in thepresence of water. The NCO end groups of the polyisocyanates react withthe water to detach CO₂ and to form longer chains through formation ofurea moieties as bridge members between pairs of isocyanate molecules.The crosslinked longer chains thus have relatively many urea moietiesand only very few urethane bonds. By contrast, polyurethanes having thestated high molecular weights have a very large number of urethane bondsin the main chain. Due to the higher molecular weights, the end groupconcentration is relatively low and the end groups themselves aredifficult to access. Crosslinking of the small number of NCO end groupspossibly present under the influence of water is therefore hardlylikely.

The following examples further illustrate details for the process ofthis invention. The invention, which is set forth in the foregoingdisclosure, is not to be limited either in spirit or scope by theseexamples. Those skilled in the art will readily understand that knownvariations of the conditions of the following procedures can be used.Unless otherwise noted, all temperatures are degrees Celsius and allpercentages are percentages by weight.

EXAMPLES

Preparation of Cationic Polyurethanes

Polyurethane 1 (Inventive)

174.5 g of toluene diisocyanate (mixture of 2,4- and 2,6-isomer in aratio of 20:80; 1.003 mol) are added to a solution of 119.2 g ofN-methyl-diethanolamine in 250 g of acetone at room temperature over thecourse of 1.5 hours. An infrared spectrum is then recorded to check ifthere are still any free isocyanate groups left over. If this is not thecase, 707 g of water and 60 g of glacial acetic acid are added as amixture. This results in the formation of a homogeneous clear liquid,from which the solvent is distilled. The distillation is terminated oncethe solids content is 29%.

Polyurethane 2 (Inventive)

168.8 g of toluene diisocyanate (mixture of 2,4- and 2,6-isomer in aratio of 20:80; 0.97 mol) are added to a solution of 119.2 g ofN-methyl-diethanolamine in 250 g of acetone at room temperature over thecourse of 1.5 hours. An infrared spectrum is then recorded to check ifthere are still any free isocyanate groups left over. If this is not thecase, 696 g of water and 60 g of glacial acetic acid are added as amixture. This results in the formation of a homogeneous clear liquid,from which the solvent is distilled. The distillation is terminated oncethe solids content is 29%.

Polyurethane 3 (Inventive)

168.5 g of hexamethylene diisocyanate (1.003 mol) are added to asolution of 59.6 g of N-methyldiethanolamine (0.5 mol) and 31.1 g ofethylene glycol in 250 g of acetone at reflux temperature over thecourse of 1.5 hours. An infrared spectrum is then recorded to check ifthere are still any free isocyanate groups left over. If this is not thecase, 580 g of water and 31.3 g of glacial acetic acid are added as amixture. This results in the formation of a homogeneous clear liquid,from which the solvent is distilled. The distillation is terminated oncethe solids content is 30.9%.

Self-dispersing Isocyanate 4 (Comparative)

85 parts by weight of an isocyanate having an NCO content of 22.5% andconsisting essentially of trimeric hexamethylene diisocyanate arereacted at 60° C. with 15 parts by weight of a polyethylene glycolmonomethyl ether having an average molecular weight of 350. Theresultant product has an NCO content of 17% and a viscosity of 1,500mPas at 25° C. The product is very efficiently dispersible in awater-filled glass beaker simply by stirring with a glass rod. Thearithmetic NCO functionality is F is 2.70.

II Finishing of Wool and Nonfelting Test

(a) Plasma Pretreatment

Moist wool slubbing is initially subjected to a corona treatment forwhich the following parameters are observed:

Frequency: 23.0 Hz Roll gap: 0.8 mm Air supply: 400.0 l/min Pulsefull-cycles on: 2 Pulse full-cycles off: 8 Spread: 1:2 Forward feedrate: 10 m/min Power: 780 W

(b) Wet Chemical Treatment

The moist wool stubbing pretreated according to step (a) is treated bythe exhaust process with a solution of the above-describedpoly-urethanes that is buffered to pH 5 via an acetic acid/acetatebuffer. When the self-dispersing isocyanate is used, a similar procedureis carried out at a pH 7, set using a phosphate buffer.

The slubbing is prewetted in warm water and whirled to spin off excesswater. The finishing bath of warm water at 40° C. is admixed with 2%(solid, based on the wool weight in the dry state) of the respectivepolyurethanes while observing a liquor ratio of 20:1. The wool remainsin the bath for 20 minutes and is then removed, squeezed off, washedthree times manually with water in a beaker, again squeezed off, andsuspended from a line to dry.

After drying, the wool is subjected to the Aachen felting ball test ofIWTO standard 20-69. The results are summarized below in Table 1:

TABLE 1 Average felting ball diameter Example Aftertreatment agent [cm]Inventive 1 Polyurethane 1 3.794 Inventive 2 Polyurethane 2 3.754Inventive 3 Polyurethane 3 3.494 Comparative 4 Self-dispersing 3.437isocyanate 4

Comparative Examples 5 and 6

In Comparative Example 5, the Aachen felting ball test is measured onthe wool following a plasma treatment only, i.e., after the step (a)described above for Inventive Examples 1 to 3 and Comparative Example 4has been carried out.

In Comparative Example 6, the wool is exclusively treated with theself-dispersing isocyanate according to the step (b) treatment describedabove for Comparative Example 4 and then subjected to the Aachen feltingball test.

A comparison of the felt densities, which are likewise measurable in theAachen felting ball test, for the different pre- and aftertreatments ofthe wool slubbing is contained in Table 2:

TABLE 2 Antifelt finishing Felt density Example process [g/cm³]Inventive 1 Wool, plasma treated + 0.036 polyurethane 1 Inventive 2Wool, plasma treated + 0.036 polyurethane 2 Comparative 4 Wool, plasmatreated + 0.04 self-dispersing polyisocyanate 4 Comparative 5 Wool,plasma treated 0.11 Comparative 6 Wool, untreated + 0.14 self-dispersingpolyisocyanate 4

What is claimed is:
 1. A process for antifelt finishing of woolcomprising (a) exposing the wool to a plasma in a pretreatment, and (b)treating the plasma-treated wool with an aqueous dispersion of cationicpolyurethanes.
 2. A process according to claim 1 wherein the plasmatreatment of the wool in step (a) is effected either as a lowtemperature plasma treatment at reduced pressure or as a coronatreatment at normal pressure.
 3. A process according to claim 1 whereinthe cationic polyurethanes have a weight average molecular weight of atleast 14,000 and the upper limit of the molecular weight is 200,000. 4.A process according to claim 1 wherein the cationic polyurethanes areobtained by reaction of (i) organic polyisocyanates of the formula (I)Q[NCO]_(p),  (I)  where p is from 1.5 to 5, and Q is an organic radical,and (ii) one or more bis- and/or polyhydroxy compounds containing atleast one tertiary nitrogen atom and at least two hydroxyl groups,wherein the cationic character of the polyurethane is generated bysubsequent protonation or alkylation of the tertiary nitrogen atoms. 5.A process according to claim 4 wherein the cationic polyurethanes areprepared by additionally using (iii) one or more bis- and/or polyhydroxycompounds containing no nitrogen atoms and having molecular weights of62 to 5,000.
 6. A process according to claim 5 wherein the bis- and/orpolyhydroxy compounds (iii) are ethylene glycol, propanediol-1,2,propanediol-1,3, butanediol-1,4, butanediol-1,3, butanediol-2,3,butanediol-1,2, butenediol-1,4, butynediol-1,4, pentanediol-1,5,neopentyl glycol, hexanediol-2,5, hexanediol-1,6,3-methylpentanediol-1,5, 2,5-dimethylhexane-2,5-diol,octadecanediol-1,12, diethylene glycol, dipropylene glycol, triethyleneglycol, tripropylene glycol, tetraethylene glycol, tetrapropyleneglycol, and higher polyethylene and polypropylene glycols, glycerol,trimethylol-propane, 2-hydroxymethyl-2-methyl-1,3-propanediol,1,2,6-hexanetriol, or pentaerythritol.
 7. A process according to claim 4wherein the bis- and/or polyhydroxy compounds (ii) are those of theformula (II) HO—(CHR¹)_(m)—NR²—(CH₂R¹)_(n)—OH  (II), where n and m areindependently from 1 to 6, R¹ is in each case independently hydrogen ora straight-chain or branched C₁-C₄-alkyl radical wherein, along the(CHR¹)_(n) and (CHR¹)_(m) alkylene chains, R¹ can alternately fromcarbon atom to carbon atom be not only hydrogen but also astraight-chain or branched C₁-C₄-alkyl radical, and R² is straight-chainor branched C₁-C₁₀-alkyl, C₁-C₁₀-cycloalkyl, C₆-C₁₂-aryl, or a—(CH₂)_(r)—OH radical in which r is from 1 to
 6. 8. A process accordingto claim 4 wherein the bis- and/or polyhydroxy compounds (ii) of theformula (II) are N-methyldiethanolamine, N-ethyldiethanolamine,N-butyldiethanolamine, N-methyldipentanolamine-1,5,N-ethyldipentanolamine-1,5, triethanolamine, reaction products of fattyamines with two moles of ethylene oxide or propylene oxide, oralkoxylation products thereof.
 9. A process according to claim 1 whereinthe cationic polyurethanes are obtained by reaction of (i) organicpolyisocyanates of the general formula (I) Q[NCO]_(p),  (I)  where p isfrom 1.5 to 5, and Q is an aliphatic hydrocarbon radical having 2 to 18carbon atoms, a cycloaliphatic hydrocarbon radical having 4 to 15 carbonatoms, an aromatic hydrocarbon radical having 6 to 15 carbon atoms, oran araliphatic hydrocarbon radical having 8 to 15 carbon atoms, and (ii)bis- and/or polyhydroxy compounds (ii) of the general formula (II)HO—(CHR¹)_(m)—NR²—(CH₂R¹)_(n)—OH  (II),  where n and m are independentlyfrom 1 to 6, R¹ is in each case independently hydrogen or astraight-chain or branched C₁-C₄-alkyl radical wherein, along the(CHR¹)_(n) and (CHR¹)_(m) alkylene chains, R¹ can alternately fromcarbon atom to carbon atom be not only hydrogen but also astraight-chain or branched C₁-C₄-alkyl radical, and R² is straight-chainor branched C₁-C₁₀-alkyl, C₁-C₁₀-cycloalkyl, C₆-C₁₂-aryl, or a—(CH₂)_(r)—OH radical in which r is from 1 to 6, and the cationiccharacter of the polyurethanes is generated by protonation or alkylationof the tertiary nitrogen atoms.
 10. A process according to claim 1wherein the cationic polyurethanes are obtained by reaction of (i)2,4-toluene diisocyanate or 2,6-toluene diisocyanate or mixtures ofthese isomers with (ii) N-methyl- or N-butyldiethanolamine, wherein thecationic character is generated by treating the obtained reactionproducts with hydrochloric acid, sulfuric acid, formic acid, aceticacid, or propionic acid.
 11. A process according to claim 1 wherein step(b) is effected by applying the aqueous dispersion of the cationicpolyurethane to the wool at a pH of 2 to
 7. 12. A process according toclaim 1 wherein the concentration of the aqueous dispersion of thecationic polyurethane, based on the solids content of polyurethane, infinishing liquor, is 0.5 to 75 g/l.